10. "Polyester plant design and engineering today and tomorrow."

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230 CHEMICAL FIBERS INTERNATIONALVolume 54, September 2004RAW MATERIALSPolyester plant design and engineering today and tomorrowU.K. Thiele, Dr. Thiele Polyester Technology, Bruchköbel/GermanySummarizing the consulting experiencesof the recent years, the essence of im-portant polyester conferences like theyearly Polyester World Congress inZurich/Switzerland and fairs likeACHEMA and ITMA, the description ofcurrent status of polyester plant designand engineering business provides aninteresting picture. One proven fact is thesignificant decline of new polyester proj-ects in Western Europe and Americaand the sharp increase of projects espe-cially in China and Eastern Europe (seepages 40-46 of this issue). At the sametime the number of companies fightingfor market shares of polyester plant en-gineering has surprisingly increased.Polyester engineering on the moveAs little as five years ago the market oflarge continuous polyester plants, evenin China, was completely dominated bythe leading engineering companies likeChemtex using DuPont technology, Zim-mer AG, Inventa-Fischer, Kanebo andHitachi whereupon large producer likeNanya, Hyosung, Eastman (Voridian),Mitsubishi, Mitsui, Toray or Tuntex tookplanning, design and erection of newplants into their own hands.Today, even with the smaller marketshares of new investments in Europe andAmerica the number of companies whichare fighting for this market and which areable to deliver world scale polyesterplants has increased remarkably. New-comers and developers in Europe likeNOYVallesina Engineering, EPC-indus-trial-engineering or AQUAFIL Engineer-ing and in China companies and designinstitutes like Huitong Polyester [1],CTIEI/CTCEC [2] and CTA/SINOPEC [3]are increasing the competition potentialenormously. Especially the market in Chi-na changed drastically. When the abovementioned leading traditional engineer-ing companies covered about 80 % of themarket share in China six years ago, thisshare has shrunk currently to less than40%, and this process is rapidly ongoing.The latest bank loan policy of the Chi-nese government especially, where in-stead of 10% now about 50% net equityis necessary for new projects, will forceChinese investors to turn to domesticengineering companies which are ableto strongly undercut the import prices.Capability to build world scale plantsLooking at the results of the recent yearsexpressed in erected and running poly-ester lines, the capabilities to build"World Scale" and competitive continu-ous polyester melt phase plants is pre-sented in Table 1.The reported numbers of plants and therelated melt phase capacities might bedifferent from source to source, but themessage is clear. Besides, China is theleading country in polyester with a pro-duction capacity of nearly 14 milliontons/year. The Chinese engineering ca-pability to build world scale melt phaseplants also has to be considered. It shouldalso be mentioned that SSP technologyfor bottle polyester in China is on the wayto becoming independent soon. At theend of 2004 Yizheng will start up its firsthomemade solid state polycondensationplant with a capacity of 275 tons/daybased on a joint development with CTIEI.Plant capacity developmentHow conservatively capacity develop-ment was seen only 8 years ago isdemonstrated in the comparison Fig.The limitation of maximum plant capaci-ty differs significantly between PET resinfor bottle applications and textile chipson the one hand and direct conversion ofmelt to textile fibers and filament yarns atthe other hand. For chip production thereis, besides mechanical limits of vesselsizes and vessel transport logistics, noreal upper limit, and plant capacities ofup to 1500 tons/day and higher will berealistic in the near future. The best ex-ample for this development is the new Al-tamira line of M&G which was originallydesigned for 750 tons/day, which hasreached an output of 1000 tons/day andwhich is under further capacity optimiza-tion. This process route is becomingmore and more comparable to the hugebulk production lines of polyolefines.As opposed to this, the direct conversionof polyester melt to textile fibers and fila-ment yarns might capacity wise be satu-have a positive consequence for technol-ogy owning engineering companies infuture. Different to the past, where largeproduction companies had the reliancein their in-house engineering to erectpolyester plants using home made, li-censed or copied technology, it will behardly probable in the future that an en-gineering department which erects anew plant every now and then will takerisk and responsibility for such large ca-pacity and investment projects. Hereagain, the cooperation between poly-ester producer and engineering might bethe most successful model.Process simplification andoptimizationBesides the steadily increasing plant ca-pacity, one can recognize the clear trendtoward the reduction in process steps.The three step process of esterification,pre-polycondensation and polyconden-sation as applied for many years by theDuPont/Chemtex technology, is becom-ing more and more common nowadays.Companies such as NOY Vallesina Engi-neering or CTA/SINOPEC are designingtheir plants based on this process phi-losophy.Significant further progress is made byInventa-Fischer with their new two stepprocess applying a tower reactor con-taining esterification and pre-polycon-densation as well in one housing as afirst reactor, and polycondensation as asecond reactor. The compact design al-lows savings in conversion cost of up to21 %, which means a reduction of totalproduction costs by 3.5-4.0 %. Havingthe small profit margins of the PET busi-ness in mind, this development might at-tract future investors. The patented"ESPREE" technology [4] has alreadybeen introduced to industrial size andexecuted in four polyester projects withcurrent largest capacity of 250 tons/day.The scale up is on the way.Another new polyester process technol-ogy called NG3 proprietary to DuPont,which was introduced to the public dur-ing the 1990s, raised high expectationsregarding savings in investment costsTable 1Established engineering companies:Chemtex/DuPont + M&G: 800 tons/day, 3-stage-process: bottle grade, in operation at about 1000 tons/day in Altamira/Mexico, further output increase is in preparationChemtex/DuPont:More than 15 lines over 500 tons/dayChemtex/DuPont (NG3) 2 lines 600 tons/day Inventa-Fischer:10 lines 500 - 600 tons/day including challenging projects such as direct processing of BOPETZimmer AG:3 lines 600 tons/day, 7 lines 300 - 500 tons/day New companies in China:CTIEI/CTCIC:20 lines 500-600 tons/day, 10 lines > 300 tons/dayCTA/SINOPEC:1 line250 tons/day, 1 line 400 tons/dayHuitong Polyester:1 line 250 tons/day, 1 line 300 tons/dayrated at about 600tons/day. The latterprocess is limitedin the residencetime of PET meltwhich should, forreasonable spin-ning results, notexceed 30-40 min-utes depending onmelt temperature.The rapidly ongo-ing capacitygrowth might alsoCHEMICAL FIBERS INTERNATIONAL 231Volume 54, September 2004RAW MATERIALSand quality improvements. Here, the tra-ditional melt polycondensation undervacuum is completely replaced by theSSP which reduces the chemical part ofthe plant to a two reactor process. Theremight be unexpected problems or hur-dles during the first industrial start up ofthe new process as there is no officialstatement on the status of the projectscurrently available.Saving costs and cutting process stepson a somewhat smaller scale is also thebackground of the recently announcedcombination of under water pelletizingand crystallization by Kreyenborg [6].Keeping sufficient heat in the pellets dur-ing the cooling period by heating up thecooling medium to a range where thepolyester chips will remain at tempera-tures between 160-110 °C provides aquick crystallization in the presence ofwater. The resulting chips have a degreeof crystallization in a range of 40 % ac-cording to Kreyenborg, which is enoughfor a safe and lump formation free dryingstep without crystallization. This technol-ogy will especially interest those proces-sors who aim for PET applications inpackaging and engineering plastics.Another path to satisfy the growth of poly-ester production, besides the erecting ofnew plants, is the substantial capacityboost of existing continuous lines. By un-derstanding process kinetics, heat man-agement and internal flow conditions indetail, it is possible to increase the plantoutput of existing plants up to the doublename plate capacity by replacing the bot-tlenecks and redesigning important sin-gle parts such as finisher internals,scraper condensers, process columns orheat transfer equipment. This field, for in-stance, is the special domain of EPC in-dustrial engineering which offers expert-ise and process knowledge to fill this mar-ket niche.Besides reduction of process steps ornumber of reactors or equipment parts,the whole production chain has to be x-Here, the physically closer coupling ofPTA and EG production with the conver-sion to polyester might provide furthercost saving potential.Direct conversion processesHaving had the good luck to have start-ed up a new process development near-ly a decade ago as co-inventor, it is nowsatisfying to notice that this technology ison the way to its first roll out soon. Meantis the direct performing or melt to pre-form process which today, is investigatedand developed by Inventa-Fischer [7]and Zimmer AG [8] in pilot scale condi-tion. Both companies presented their ex-perimental concept in pilot scale togeth-er with the melt to preform machinery tothe interested public. Some details e.g.how to reduce the AA-content to the de-manded low AA-level for water packag-ing without spoiling the polymer byadding high amounts of AA-scavengers,or how to manage the seasonable andfashion driven flexibility of preform de-signs, are still under question. Yet like 35years ago the step from extrusion spin-ning to direct spinning, which was drivenby enormous cost savings, the melt topreform process will become reality inthe near future. It would be recommend-able for those who are producing pre-forms now and who are still skepticalabout the future development of theirbusiness to have a deeper look at con-tinuous direct spinning- and fully-auto-mated POY plants as they are newly in-stalled at large textile yarn produceraround the world.The direct preforming plant capacitymight start at an output range of about100-200 tons/day which means at like-wise low melt phase capacity. The wellknown correlation between plant capaci-ty and conversion cost where the largestmelt phase capacity secures the lowestcost might raise the question of theeconomy of scale for this new direct pre-forming process.Yet as shown in the pre-vious passage there is new design for atwo reactor compact melt phase poly-condensation of 200 tons/day alreadyavailable on the market. Finally, one hasto puzzle the currently present best tech-nologies together, and of course onemust take the comparable high risk tobecome the first user of direct preform-ing technologyAt this point the largest direct conversionfilm project must be mentioned. Out of amelt phase finisher of a capacity of 600tons/day polyester melt 400 tons/daythereof will be directly converted to biax-ial oriented film in a thickness range of12-36 ?m in four parallel lines of a ca-pacity of 100 tons/day each. The remain-ing 200 tons/day polyester melt are con-verted to film granulate.This project is un-der construction in China.The melt phaseplant which provides the film polymer tothe BOPET lines including the melt dis-tribution to the single film lines is de-signed and executed by Inventa-Fischer.Future prospectsIn summary it can be said that polyesterplant design and related engineering busi-nesses are under increasing competitionpressure whereas the serial erection ofstandard type polyester plants in China atsizes up to 600 tons/day is on the move toChinese engineering companies. As aconsequence, one could expect Chineseengineering activities outside of China af-ter the Chinese market is saturated. Tosustain and even grow in this businessthus needs a straight-forward and longterm research and development commit-ment in order to serve customers with highquality and cost saving polyester produc-tion and conversion technology. Besidesfurther substantial capacity increases,there are process simplifications and fur-ther integration to raw material produc-tion, direct conversion melt to preform ormelt to film, as well as intelligent plant op-timization and the revamp of importantfields to be distinguished from me too en-gineering. Not forgetting the myriads ofthe existing discontinuous and low ca-pacity continuous lines. To survive in themarket they will need to produce highlyspecialized polyester products, which isanother field of know-how developing en-gineering companies.Literature[1] www.chinapolyester.com/[2] www.ctiei-overseas.com/index.html[3] www.cta.com.cn/en/intro.shtm[4] Schumann, H.-D. Thiele, U.K., Polyester Produc-ing Plants, Verlag moderne industrie, 1996[5] WO 03/042278von Endert, E., Chemical Fibers International,54 (2004) 164-166[6] WO2004033174[7] EP0727303[8] US5656221Chemical Fibers International 54 (2004) 161Development of capacity: figure published in 1996 [4] and the current situation rayed to cut pro-duction costs andto simplify technol-ogy or distributionlogistics. Becausesavings in trans-port and ware-house costs arebecoming increas-ingly importantwith declining mar-gins, there is stillspace for develop-ment for thosecompanies whichare fully integratedwith the raw mate-rials PTA and EG.